Pretreatment and cracking of heavy mineral oils



United States Patent 3,165,462. PRETREATMENT AND CRAtIKiblG (9F HEAVYMINERAL 0115 Bernard S. Friedman, Chicago, and James P. Gailagher, ParkForest, 15., assi nors, by mesne assignments, to Sinciair Research, Inc,New York, N.Y., a corporation of Delaware 7 Filed Aug. 10, 1961, Ser.No. 1313513 Ciaims. (Cl. 268-86) This invention concerns the catalyticcracking of heavier mineral hydrocarbon oils to obtain lightercomponents including gasoline of relatively high octane number. Moreparticularly, the present invention relates to an improved process forthe treatment of metal contaminated hydrocarbon oils in which theharmful effects of the metal contaminants on the cracking operation areavoided.

The present invention comprises pretreating a petroleum hydrocarbonfeedstock boiling above the gasoline range with acid, subjecting thetreated feedstock to catalytic cracking and demetallizing the crackingcatalyst. The acid treatment serves to remove some aromatic and heterocomponents such as nitrogen-, oxygenand sulfurcontaining compounds whichare present in most heavy hydrocarbon feeds and interfere with thecracking operation, and also serves to remove some of the metalcontaminants from the feedstock.

In this invention an operation involving feed pretreatment and catalyticcracking of heavier mineral hydrocarbon oil feedstocks to producegasoline is combined with a procedure for reducing poisoning metals onthe cracking catalyst to present a much more attractive answer to theproblem of catalyst poisoning by heavy metals than either feed treatmentor catalyst demetallization alone. Catalyst demetallization alone wouldnot overcome the problem of coke laydown in cracking which is caused bya large asphaltene content in the feed and further would requireenormous demetallization facilities to deal with a heavily contaminatedfeed. Likewise, acid treatment does not ordinarily produce in a simpletreatment of a heavily poisoned feedstock, a catalytic cracking feed solow in poisoning metals that their effect on the cracking operation canbe ignored.

The catalytic cracking of various heavier mineral hydrocarbons, forinstance petroleum or other mineral oil distillates such as straight runand cracked gas oils; shale oils; etc., has been proposed for many yearsand the catalytic cracking of gas oils is practiced commercially to aconsiderable extent. As is well known to those familiar with the art,gas oil is a broad, general term that covers a variety of stocks. Theterm includes any fraction distilled from petroleum or other mineral oilwhich has an initial boiling point of at least about 400 F., say, up

to about 850 F., and an end boiling point of at least about 600 F., andboiling substantially continuously between the initial boiling point andthe end boiling point. Usually the boiling range extends over at leastabout 100 F. The portion which is not distilled before the end point isreached is considered residual stock. The exact boiling range of a gasoil, therefore, will be determined by the initial distillationtemperature (initial boiling point) and by the temperature at whichdistillation is cut off (end boiling point). In practice, petroleumdistillations have been made under vacuum up to temperatures as high asabout 1100-1200 F. (corrected to atmospheric pressure). Accordingly, inthe broad sense,- a gas oil is a petroleum fraction which boilssubstantially continuously between two temperatures that establish arange -j falling within from about 400 F. to about 1100-1200 F. Thus, agas oil could boil over the entire range about 4001200 F. or it couldboil over'a narrower range, eg.

about 500-900 F. The gas oils can befurther roughly Patented Jan. 12,1965 classified by boiling ranges. Thus, gas oil boiling between about400-500 F. and about 600-650" F. is termed a light gas oil; a medium gasoil distills between about 600-650 F. and about 800-900 F.; a gas oilboiling between about 800-850 F. and about 1100-1200" F. is sometimesdesignated as a vacuum gas oil. It must be understood, however, that aparticular stock may bridge two boiling ranges, or even span severalranges, i.e. include, for example, light and medium gas oils.

A residual stock is in general any petroleum fraction higher boilingthan a selected distillate fraction. Any fIaCllOH IEgZIIdESS of itsinitial boiling point, which includes heavy bottoms, such as tars,asphalts, or other nondistilled material may be termed a residualfraction. Accordingly, a residual stock can be the portion of the cruderemaining undistilled at about 1100-1200 F., or it can be made up of agas oil fraction plus the portion undistilled at about 1100-1200" F. Forinstance, a Whole. topped crude, is the entire portion of the cruderemain-. ing after the light ends (the portion boiling up to about 400F.) have been removed by distillation. Therefore, such a fractionincludes the entire gas oil fraction (400- F to 1100-1200 F.) and theundistilled portion of the crude petroleum boiling above 1100-1200 F.

The behavior of a hydrocarbon feedstock in the cracking reactionsdepends upon various factors including its boiling point, carbon-formingtendencies, content of catalyst contaminating metals, etc., and thesecharacteristics may affect the operation to an extent which makes agiven feedstock uneconomical to employ.

By and large, residual stocks have notbeen catalytically cracked on acommercial scale as their carbon-forming tendencies and catalystpoisoning metals content are generally too great. It has long beenrecognized that residua and petroleum gas oils which includeconstituents boiling in excess of about 950 F. normally contain nickeland vanadium and other metallic contaminants which have an adverseeffect upon various catalysts employed in petroleum processingoperations. In operations such as catalytic cracking and the like, thepresence of very small concentrations of these contaminants in the feedstream leads to the rapid poisoning of the catalyst, causing asignificant decrease in the product yield, an increase in coke and gasproduction and a marked shortening in the life of the catalyst. Also,some residual stocks are so heavily metals-contaminated that their useeven as a fuel is limited,

0 since such contaminants attack the refractories used to highaccumulation of poisoning metals in the cracking system, this type ofoperation represents a substantial cost factor. Improvement in thefeedstock characteristics become even more important as the cost of thecatalyst rises and thus the effects of low feedstock quality areparticularly burdensome in systems employing cracking catalystscontaining relatively expensive synthetic com ponents.

Although there have been numerous methods proposed in the past forremoving contaminants from high boiling petroleum fractions, it has beenfound that when a severely contaminated feed is used, such methods arenot fully effective, generally'result in loss of substantial quantitiesof the oil, and in many cases are prohibitively expensive.

As a result, it has generally been necessary to restrict the feedstreams to catalytic petroleum processing units to those fractions whichboil below. the range in which the contaminants are found and to avoidasmuch as possible from 15 to about 150-200 p.s.i.g. the percent ofprecipitate is greatly increased. The concentration of the precipitatinga ent may be regulated by pressure for particular crude oils which varyin asphaltic content or in content of metals and which vary somewhat insolubility for hydrogen chloride. The effectiveness of the treatment isincreased by mild agitation which assists in saturating the crude oilwith the precipitating agent and agglomerating sludge particles. 1

Some residual stocks, such as vacuum topped crudes, have been found tooviscous for easy intimate contact and effective saturation of theresidual with the precipitating agent. Also, the viscosity tends toprevent the precipitates from quick complete settling out from thetreated oil. Therefore materials which act as diluents and/or solventextracting agents frequently must be added to the feedstock. Suchmaterials are generally of the type useful in extracting lubricatingoils, gas oils and the like. The diluent or solvent may be chosen from anumber of hydrocarbon types, as well as other extracting solvents orcounter solvents well-known in the art, such as S Whole crude oil orstraight-run naphthas may be used, but especially suitable solvents arethe liquified hydro carbons of about 3 to 7 carbon atoms, preferably ofabout 3 to carbon atoms. The solvent is normally employed in asolvent-to-oil ratio of from about 0.5/1 to 20/1 and preferably thesolvent-to-oil ratio is about 1/1 to 10/1. At least about 75 weightpercent, usually about 80 to 95 weight percent of the feed to thetreating zone is recovered.

When the presence of the diluent is necessary for proper contact betweenacid and hydrocarbon feedstock the diluent is added to the feed beforeor simultaneously with the acid. Alternatively, the solvent may be usedmerely to complete precipitate removal. In such practice, the acid iscontacted and mixed with the charging stock to saturate the residual oiland then the charging stock is extracted with the selective solvent toform a raffinate phase containing the precipitate and an extract phasewhich contains the treated oil, free of precipitating components. Thesludge or precipitate, of course, contains a substantial portion of themetal content, coke precursors and some other undesirable materialsoriginally present.

The method of contacting the residual feed, that is, whether theselective solvent will be added along with the acid or subsequent to theacid contact, will depend to some extent upon the acid that is used. Forinstance, when a residual oil is subjected to treatment with a hydrogenhalide gas, such as hydrogen chloride, slightly elevated pressures andtemperatures sufficient to reduce the viscosity of the oil are generallyused. While no sludge is collected during addition of this acid, contactof the treated oil with a solvent will precipitate the in solublematerial containing a substantial portion of the metal poisons and cokeprecursors originally present. When a liquid acid such as xylenesulfonic acid is used as the contacting agent, the solvent is preferablyadded along with the acid to reduce the viscosity of the feed as well asto permit separation of the sludge formed. However, either sequence ofcontacting steps can generally be adapted for either type of treatingagent.

The precipitate-free oil may be washed with an aqueous medium such aswater or an alkaline solution or blown with an inert gas to free the oilor residual amounts of acid which may have remained in the treated '00.The acid component dissolves in the aqueous phase and is separated fromthe treated oil. The oil that is separated from the precipitated metalcontaminants is conducted to a fractionation tower where distillationtemperatures are maintained. An overhead fraction boiling below about400 F. is removed from the tower. Distillation also will remove anyhydrocarbon or other volatile solvent used in the acid pretreatment, aswell as any traces of hydrogen halide not removed by the water wash.Each of these components is usually recycled back to the treating zone,with an intermediate purification procedure if necessary. The 400F.+bottoms from the fractionation is fed to the catalytic cracker. Thisbottoms frac tion contains the entire gas oil fraction and theundistilled portion of the crude petroleum boiling above about ll001200F.

The acid sludge is withdrawn from the precipitate-free oil layer and maybe treated with water or a caustic scrubhing to remove the residual acidfrom the sludge. 'The acid may then be recycled, with or withoutpurification back to the treating zone where the fresh hydrocarbon oilis contacted with the acid. Another aspect of this invention ispresented when the demetallization procedure, to be describedhereinafter, utilizes a chlorination process for catalystdemetallization. T he chlorinator efiluent from the demetallization unitconsists primarily of hydrogen chloride, chlorine, inert gases and metalchlorides. The metal chlorides may be condensed from the vapors as byindirect cooling with water and the remaininghydrogenchloride-containing gas stream collected for hydrogen chloridepretreatment of the charging stock. This gas may be combined with thehydrogen chloride that has been removed from the treated oil and/or thesludge by water washing and/ or by distillation.

Pretreatment of the charging stock with the acidic material gives apartial reduction in metals content of the treated oil. In thisinvention pretreatment may remove only about 10% of the poisoning metalin the feedstock, but preferably much more of the poison. Thus thetreated oil or the portion used in cracking contains perhaps about 4090or more Weight percent less of one or both of nickel and vanadium thanthe hydrocarbon charged to the pretreatment reaction; preferably, thereis this much reduction in nickel and vanadium or in each of thesemetals. Frequently the reduction of one or all of the nickel, andvanadium will be about 50-90 weight percent. But pretreatment of thefeedstock usually does not remove metal contaminants to a point that isinsignificant in subsequent catalytic cracking. The amount of metal tobe removed from the feed is, in turn, determined by a number of factors:the amount of poison remaining in the pretreated oil, the proportion ofpretreated oil sent to the catalytic cracking, the amount of otherhydrocarbon material with which the pretreated oil is blended to preparethe cracker feed, and the poisoning metal content of this additionalfeedstock. The metals remaining in the pretreated oils accumulate on thecatalyst during the cracking operation and unless steps are taken toprevent excess accumulation, excessive dehydrogenation takes place incatalytic cracking, severely reducing the yield of gasoline in thecracker efiluent. The pretreated oil, before any other material isblended has a least about 1.0 ppm. nickel and/ or 2 ppm. vanadium andhas a preferred maximum metal content of about 25 ppm. nickel and/or 50ppm. vanadium.

The portion of the pretreated oil boiling above 400 F. may be combinedwith other cracking feed in any proportion, but the cracker feedpreferably contains at least about 10% of the treated oil, preferablyabout 20 to 70%. The remaining portion of the cracker feed may comprisecracking feeds of more or less conventional types, that is, virgin gasoil fractions or recycle gas oils from this cracker or other catalyticcrackers, etc. Alternatively, the entire effluent can be sent to thecracker without diluting with extraneous feed material. Pretreatmentconditions and the proportion of the treated oil boiling above about 400P. included in the cracker feed will be adjusted to provide a feedcontaining more than about 1.0 ppm. nickel and/or 1.0 ppm. vanadium inorder to justify the provisions made in this invention for crackingcatalyst demetallization and preferably the total feed to cracking willcontain more than about 1 ppm. nickel and/ or 2 ppm. vanadium but oftenless than about 10 ppm. nickel and/or 25 ppm. vanadium. At least about 1ppm. nickel and/ or about 1 or 2 ppm. vanadium is contributed to thecracked feed by the treated oil boiling about 400 F. The use tion unitwiththe catalytic cracker counteracts this remaining metal content,'thereby enabling processing of a much deeper cutiof the crude stock. 1 i

Catalytic'cracking is ordinarily effected to produce gasoline as themost valuable product. The feed to the cracking zone is substantiallyvaporized and catalytically treated under more orless conventional fluidcatalytic cracking conditions. Cracking is generally conducted attemperatures of about 750 to 1000 F., preferably about 850to 975 F, anda pressure between atmospheric and about of a catalystdemetallizaij cokefrom the catalyst" is "economy only' enough air is used to supply theneeded oxygen; Average residence time for a portion of catalyst in theregenerator may be. of the order of about six minutes and the. oxygencontent. of the .efiluent gases from the regenerator is desirably lessthan about /2%; The regeneration of any particular quantumv of catalystis gen- 100 p.s.i.g., preferably about atmospheric to' 5-25 p.s.i.g., L

at, a weight hourly space velocity from about 0.1 to to obtain about a40-80 volume percent, preferably about i 50 to 65%, conversion of thecatalytic feedstock to gasoline and other desired lighter components.

The products'of the cracking-are conducted to afractionation columnwhere the lower boiling gasoline constituents'of the cracker effluenthaving an approximate 375 430 F. end point are vaporized and removedfrom the system and may be used as gasoline blending components or otherproducts. Also, products, as gases, boiling erally regulated to give acarbon content of less than about 5.0%, generally less than about 0.5%.Regeneration puts; the catalyst in a substantially carbon-free state,that is, the

state Where'little','if any, carbon is burned or oxygen consumed evenwhen the catalyst is contacted with oxygen at temperatures conducive tocombustion.

In the treatment to take poisoning metals from the cracking catalyst theamount of metal is removed which is necessary to keep the average metalcontent of the catalyst in the cracking system below the limit of'theunits tolerbelow the gasoline range are removed from the system. 7

The gas oil cycle. stock, usually boiling between about 7 400 F. andabout 850-950 F. may be sent back to the treating zone or catalyticcracking zone by blending it with the petroleum feedstock and/ or thepoisoned bottoms fraction.

weight condensed ring aromatic hydrocarbons. This cycle oil maytherefore advantageously be brought back to the V treating zone andcontacted along with the charge stock with the treating acid. Thetreatment results in substantial reduction of'metal contaminants andcoke precursors from the charge stock and substantial'reductionin therefractory aromatic hydrocarbons present in the cycle oil. The materialboiling above about 950 F. may be removed from the system and used as aresidual fuel component. In the cracking operation a batch,semi-continuous or continuous system may be used but most often is acontinuous fluidized system. i i

The cracking catalyst is of the solid refractory metal oxide type knownin the art, for instance silica, alumina, magnesia, titania, etc, ortheir mixtures. portance are the syntheticgel-containing catalysts, suchOf most imas the synthetic and the semi-synthetic, i.e. syntheticgelsupported on a carrier such as natural clay, cracking catalysts; Thecracking catalysts which have received the widest acceptance today areusually predominantly silica, that is silica-based, and may containsolid acidic oxide promoters, e.g. alumina, magnesia, etc., with thepromoters usually being less than about of the catalyst, preferablyabout 5 to 25%. These compositions are calcined to a state of veryslight hydration. The crack ing catalyst can be of macrosize, forinstance, bead form or finely divided form, and employedasia fixed'rnoving' or fluidized bed. In a highly preferred form" of thisinvention finely divided (fluidized) catalyst, for instance havingparticles predominantly in the 20 to 150 micron range, is disposed as afluidized bed in thereaction zone to which the feed is chargedcontinuously A portion'of the catalyst is continuously ,withdrawn andpassed to a regeneration zone Where coke or carbon is with a freeoxygen-containing gas before its return to the reaction zone. Incracking, coke yield maybe held'to a minimum through the use of goodsteam stripping and a high steam partial pressure. Regeneration of acatalyst to remove 'carbonis a relatively quick procedure in mostcommercial catalytic conversion operations. For example,

" in a typical fluidizedcracking unit, a portion of catalyst iscontinually being removed'from the reactor and sent to the regeneratorfor contact with air at about 950 to 1 2001 F.,' more usually about 1000to 1150 F. Combustion of These cycle oil fractions are substantiallyfree I of metal'poisons. The cycle oil and in particular the por-I tionboiling above about 750 F.'is rich in high molecular ance for poison.The toleranceofthe cracker for poison in turn determines to a largeextent the amount of metals removed in the catalyst dernetallizationprocedure. Where the catalyst contains a greater amount of poisoningmetal, a particular treatment will remove a greater amount of metal; forexample, if the cracker can tolerate an average of 100 ppm. Ni and thedemetallization process can remove 50% of the nickel content ofthecatalyst, only .50 ppm/of nickel can be removed in a pass through thecatalyst demetallization system; However, where the cracker can-tolerate500 ppm. of nickel, it is possible to remove 250 .p.p.m. nickel from thecatalyst with each pass through the demetallization system. it isadvisable,

Qtherefore, to operate the cracking and demetallization procedures witha catalyst having a metals content near the limit of tolerance of thecracker for poisoning metals.

In the treatment to take poisoning metals from the cracking catalyst alarge or small amount of metal can be removed as desired. 7 The.demetallization treatment generally removes about 10m 90% of oneor morepoisoning metals from a catalyst portion which passes through thetreatment. Advantageously a demetallization system is used' whichremovesabout 60 to 90% nickel and 20-40% vanadium from the treatedportion of catalyst. Preferably at least of the equilibrium nickelcontent and 15% of the equilibrium-vanadium content is removed. 'Theactual'time or extent of treating depends on various factors, and iscontrolled by the operator 7 according .to the situation he faces, e.g.the extent of metals content in the feed, the level of conversion unittolerance for poison, the sensitivityof'the particular cata lyst towardaparticular phase of" the demetallization procedure, etc. Also, thethoroughness of treatment of any quanturn'of catalyst incommerc'zialpractice is balanced against the demetallization rate chosen; that is,the amount V of catalyst, as'compared to the total catalyst in theconvertion treatment per unit of time.

burned from the catalyst in a fluidized bed by contact sion systemproper, which is'subje'cted to the demetalliza- A high rate of catalystwithdrawal from the conversion system and quick passage through a milddemetallization procedure may suffice as readily as a more intensivedemetallization at a slower rate to keep the total of poisoning metal inthe conversion reactor within the tolerance of the unit for poison. In acontinuous operation of the commercial type a satisfactorytreatingflrate maybe about 5 to 50% of the total catalyst inventory inthe system, per twenty-four hour day of operation although'othertreating rates maybe used. With a continuously circulating catalyststream, such as in the ordinary ffluid system a slip-stream ofcatalyst,"

at the equilibrium level of poisoning metals may be pid. and for reasonsof 59 removed intermittently or continuously from the regeneratorstandpipe of the cracking system. The catalyst is subjected to one ormore of the demetallization procedures described hereinafter and thenthe catalyst, substantially reduced in contaminating metal content, isreturned to the cracking system.

The dernetallization of the catalyst will generally include one or moreprocessing steps. Copending patent applications Serial Nos. 758,681,filed September 3, 1958; 763,833 and 763,834, filed September 29, 1958;767,794, filed October 17, 1958; 842,618, filed September 28, 1959;849,199, filed October 28, 1959; 19,313, filed April 1, 1960; 38,810,filed June 30, 1960; 47,598, filed August 4, 1960; 53,380, filedSeptember 1, 1960; 53,623, filed September 2, 1960; 54,368, 54,405 and54,532, filed September 7, 1960; 55,129, 55,160 and 55,184, filedSeptember 12, 1960; 55,703, filed September 13, 1960; 55,838, filedSeptember 14, 1960; 67,518, filed November 7, 1960; 73,199, filedDecember 2, 1960; and 81,256 and 81,257, filed January 9, 1961; all ofwhich are hereby incorporated by reference, describe procedures by whichvanadium and other poisoning metals included in a solid oxidehydrocarbon conversion catalyst are removed by dissolving them from thecatalyst or subjecting the catalyst, outside the hydrocarbon conversionsystem, to elevated temperature conditions which put the metalcontaminants into the chloride, sulfate or other volatile,water-dispersible or more available form. A significant advantage ofthese processes lies in the fact that the overall metals removaloperation, even if repeated, does not unduly deleteriously affect theactivity, selectivity, pore structure and other desirablecharacteristics of the catalyst.

Treatment of the regenerated catalyst with molecular oxygen-containinggas is employed to improve the re moval of vanadium from the poisonedcatalyst. This treatment is described in copending application SerialNo. 19,313, filed April 1, 1960, and is preferably performed at atemperature at least about 50 F. higher than the regenerationtemperature, that is, the average temperature at which the major portionof carbon is removed from the catalyst. The temperature of treatmentwith molecular oxygen-containing gas will generally be in the range ofabout 1000 to 1800" F. but below a temperature where the catalystundergoes any substantial deleterious change in its physical or chemicalcharacteristics, preferably a temperature of about 1150 to 135 F. oreven as high as 1600 F. The duration of the oxygen treatment and theamount of vanadium prepared by the treatment for subsequent removal isdependent upon the temperature and the characteristics of the equipmentused. If any significant amount of carbon is present in the catalyst atthe start of this high-temperature treatment, the essential oxygencontact is that continued after carbon removal, which may vary from theshort time necessary to produce an observable effect in the latertreatment, say, a quarter of an hour to a time just long enough not todamage the catalyst. In any event, after carbon removal, the oxygentreatment of the essentially carbon-free catalyst is at least longenough to provide, by conversion or otherwise, a substantial amount ofvanadium in its highest valence state at the catalyst surface, asevidenced by a significant increase, say at least about preferably atleast about 100%, in the vandium removal in subsequent stages of theprocess. This increase is over and above that which would have beenobtained by the other metals removal steps without the oxygen treatment.The maximum practical time of treatment will vary from about 4 to 24hours, depending on the type of equipment used. The oxygen-containinggas used in the treatment contains molecular oxygen as the essentialactive ingredient and t ere is little significant consumption of oxygenin the treatment. The gas may be oxygen, or a mixture of oxygen withinert gas, such as air or oxygen-enriched air, containing at least about1%, preferably at least about 1.0% 0 The partial pressure of oxygen inthe treating 10 gas may range widely, for example, from about 0.1 to 30atmospheres, but usually the total gas pressure will not exceed about 25atmospheres.

The catalyst maypass directly from the oxygen treatment to a vanadiumremoval treatment especially where tms is the only importantcontaminant, as may be the case when a feed is derived, for example,from Venezuelan crude. Such treatment may be a basic aqueous wash suchas described in copending patent applications Serial No. 767,794, andSerial No. 39,810. Alternatively vanadium may be removed by achlorination procedure as described in copending application Serial No.849,199. Vanadium may be removed from the catalyst after the hightemperature treatment with molecular oxygen-containing gas by washing itwith a basic aqueous solution. The pH is frequently greater than about7.5 and preferably the solution contains ammonium ions which may be inthe form of NH,} ions or organic-substituted NH4+ ions such as methylammonium and quatenary hydrocarbon radical ammoniums. The amountofammonium ion in the solution is sufiicient to give the desired vanadiumremoval and will often be in the range of about 1 to 25 or more poundsper ton of catalyst treated. The temperature of the wash solution mayvary within wide limits: room temperature or below, or higher.Temperatures above 215 F. require pressurized equipment, the cost ofwhich does not appear to be justified. Very short contact times, forexample, about a minute, are satisfactory, while the time of washing maylast 2 to 5 hours or longer. After the ammonium wash the catalyst slurrycan be filtered to give a cake which may be reslurried with water orrinsed in other ways, such as, for example, by a water wash on thefilter, and the rinsing may be repeated, if desired, several times.

Alternatively, after the high temperature treatment withoxygencontaining gas, treatment of a metals contaminated catalyst with achlorinatnig agent at a moderately elevated temperature up to about 1000F. is of value in removing vanadium and iron contaminants from thecatalyst as volatile chlorides. This treatment is described in copendingapplication Serial No. 849,199; 54,405; 54,532; 55,703; and 67,518. Thechlorination takes place at a temperature of at least about 300 F. up toabout 1000 F, preferably about 550 to 650 F. with optimum resultsusually being obtained near 600 F. The chlorinating agent is essentiallyanhydrous, that is, if changed to the liquid state no separate aqueousphase would be observed in the reagent.

The chlorinating reagent is a Vapor which contains chlorine or sometimesHCl, preferably in combination with carbon or sulfur. Such reagentsinclude molecular chlorine but preferably are mixtures of chlorine with,for example, a chlorine substituted light hydrocarbon, such as carbontetrachloride, which may be used as such or formed in-situ by the useof, for example, a vaporous mixture of chlorine gas with low molecularweight hydrocarbons such as methane, n-pentane, etc. About 1-40 percentactive chlorinating agent based on the weight of the catalyst isgenerally used. The carbon or sulfur compound promoter is generally usedin the amount of about 1-5 or 10 percent or more, preferably about 2-3percent, based on the weight of the catalyst for good metals removal;however, even it less than this amount is used, a considerableimprovement in metals removal is obtained over that which is possible atthe same temperature using chlorine alone. The chlorine and promoter maybe supplied individually or as a mixture to a poisoned catalyst. Such amixture may contain about 0.1 to 50 parts chlorine per part of promoter,preferably about 110 parts per part of promoter. A chlorinating gascomprising about 1-30 weight percent chlorine, based on the catalyst,together with one percent or more S Cl gives good results. Preferably,such a gas provides 11() percent C1 and about 1.5 percent S Cl based onthe catalyst. A saturated mixture of CC], and C1 or removal, this washpreferably takes place before the ammonium wash.

Alternative to the removal of poisoning metals by procedures involvingcontact of the sulfided or sulfated catalyst with aqueous media, nickelpoison and some iron may be removed through conversion of the nickelsulfide to the volatile nickel carbonyl by treatment with carbonmonoxide, as described in copending application Serial No. 47,598. Insuch a procedure the catalyst is treated with hydrogen at an elevatedtemperature during which nickel contaminant is reduced to the elementalstate, then treated, preferably under elevated pressure and at a lowertemperature with carbon monoxide, during which nickel carbonyl is formedand flushed oil the catalyst surface. Hydrogenation takes place at atemperature of about 800 to 1600" F., at a pressure from atmospheric orless up to about 1000 p.s.i.g. with a vapor containing to 100% hydrogen.Preferred conditions are a pressure up to about p.s.i.g. and atemperature of about 1100 to 1300 F. and a hydrogen content greater thanabout 80 mole percent. The hydrogenation is continued until surfaceaccumulations of poisoning metals, particularly nickel, aresubstantially reduced to the elemental state. Carbonylation takes placeat a temperature substantially lower than the hydrogenation, from aboutambient temperature to 300 F. maximum and at a pressure up to about 2000p.s.i.g., with a gas containing about 50-100 mole percent CO. Preferredconditions include greater than about 90 mol percent CO, a pressure ofup to about 800 p.s.i.g. and a temperature of about l00l80 F. The COtreatment serves generally both to convert the elemental metals,especially nickel and iron to volatile carbonyls and to remove thecarbonyl.

After the ammonium wash, or after the final treatment which may be usedin the catalyst demetallization procedure, the catalyst is conductedback to the cracking system. Where a small amount of the catalystinventory is demetallized, the catalyst may be returned to the crackingsystem, preferably to the regenerator standpipe, as a slurry in itsfinal aqueous treating medium. Where a large amount of catalystinventory is treated, lest the water put out the fire or unduly lowerthe temperature in the regenerator, it may be desirable first to dry awet catalyst filter cake or filter cake slurry at say about 250 to 450F. and also, prior to reusing the catalyst in the cracking operation itcan be calcined, say at temperatures usually in the range of about 700to 1300 F. Prolonged calcination of the catalyst at above about 1100 F.may sometimes be disadvantageous. Calcination removes free water, if anyis present, and perhaps some but not all of the combined water, andleaves the catalyst in an active state without undue sintering of itssurface. Inert gases such as nitrogen frequently may be employed aftercontact with reactive vapors to remove any of these vapors entrained inthe catalyst or to purge the catalyst of reaction products.

The demetallization procedure employed in this invention has been foundto be highly successful when used in conjunction with systems employingfluidized cracking catalyst to control the amount of metal poisons onthe catalyst. When such catalysts are processed, a fluidized solidstechnique is recommended for these vapor contact demetallizationprocedures as a way to shorten the time requirements. Any given step inthe demetallization treatment is usually continued for a time sufiicientto effect a substantial conversion or removal of poisoning metal andultimately results in a substantial increase in metals removal comparedwith that which would have been removed if the particular step had notbeen performed. After the available catalytically active poisoning metalhas been removed, in any removal procedure, further reaction time mayhave relatively little effect on the catalytic activity of thedepoisoned catalyst, although further metals content may be removed byrepeated or other treatments.

This invention will be better understood by reference to theaccompanying drawing which shows the schematic of a representativeprocessing system but is not to be construed as limiting.

A feed contaminated with poisoning metals, for example crude oil, vacuumgas oil or a vacuum asphalt, is fed by line 10 to treating zone 12. Acidis brought into zone 12 by line 14. When a solvent is to be used it maybe introduced into the treating zone by line 16. The treating zone maycomprise one or more towers or other vessels adapted to permit thesaturation of the oil with the acid. Suitable coils, jacketing or othertemperature control means are provided, as are means for agitation. Zone12 is usually equipped with acid gas vent line 18 which runs into acidgas recycle line 20 and associated compressor 22 for recycling to zone12. Reaction conditions within zone 12 are temperatures ranging fromabout 50 to 500 F. and pressures in the range of 25 to 600 p.s.i.g. Theresidence time of the oil may range from 5 minutes to 2 hours. An upperlayer of treated oil containing a deashed oil-solvent mixture, alongwith the acidic coagulating component is passed by line 24 to a waterwashing vessel 25, while a lower layer constituting acid sludge may bewithdrawn from the bottom of zone 12 through line 23 for disposal asdesired. In the practice of this invention acid sludge may be treated bymeans of a Water or caustic scrubbing in tank 30 to recover entrainedacid component which after removal of water can be recycled back totreating zone 12, by lines 32 and 14.

The treated oil is contacted in zone 26 with water which is introducedby means of line 34 preferably as steam. Temperature and pressureconditions in zone 2-6 are adjusted to secure the desired removal ofacid component from the oil. Washing zone 26 may comprise any suitablenumber and arrangement of stages. The Water-acid layer is separated andremoved by means of line 36. The acid component may be removed from thewater and recycled back to zone 12 by means not shown. The treated andwashed oil is removed from zone 26 by means of line 38 and brought tofractionation tower 40. The fractionator separates any acid componentthat has not previously been removed in the Washing zone 26, and theacid may be conducted by lines 41, 20 and 14 back to the treating zone.Line 42 removes gases having about 1 to 4 carbon atoms and line 44removes gasoline components and any naphtha or distillate fraction ofsimilar boiling point. The bottoms fraction boiling above about 400 F.is removed by line 48 and brought to the cracking unit 46 by line 52.The bottoms fraction may be blended with other cracking feed componentsfrom an external source 50 along with any additional cracking feedcomponents to make up the final cracking feed.

The cracker feedstock and fluid cracking catalyst are brought to thecracker 46 by the line 52. The cracker may be provided with the cycloneseparator 54 to disentrain catalyst fines from the cracker effluentwhich leaves by line 56. This effluent is brought to fractionator 58where components of the cracker efiiuent are withdrawn by line 60 forgases, line 62 for gasoline, line 64 for distillate componentscomprising light cycle oils and line 66 for materials higher boilingthan the distillate oil. Fractionator 58 may be a plurality of stagesbut in the practice of this invention a single stage fractionatorusually sutfices. The heavy components may be withdrawn from the systemby line 68, or alternatively they may be recycled by lines 70, 72, and10 to the treating zone along with distillate components from thecracker effluent from line 6 but preferably the cycle oil fraction inthe cracker effluent is recycled to the catalytic cracker by lines 66,70, 72, 76 and 52, since it is substantially poisonfree.

Contaminated catalyst is continuously remo'ed from the cracker 46 by thestandpipe 77 whence it is conducted, for example, by air from the source78 to the regenerator 80 by the pipe 32. The regenerator is providedwith the regenerator standpipe 86 for demctallization. The

drawing illustrates a demetallization system which includes apparatusfor sulfiding, chlorinating, washing and filtering the catalyst. Pipes88 and 90 conduct the catalyst to an outer chamber 92 of the sulfider 04where V the catalyst may be preheated before entering the main chamberthrough opening 96. In the sulfider the cat.- alyst passescountercurrently as a fluidized bed to sulfiding vapors entering by line98. 'aCtalyst exits by line 100 and waste sufiding gas exits by line102. Line -0 I brings the catalyst to chlorinator 104 where "it passescountercurrent to chlorinating vapor entering from line 106. -Exhaustchlorinating vapor and vaporized metal compounds leaveby line 108 andcatalyst, reduced in vanadium content passes by line 110' to slurry tank112 which is kept supplied with water, perhaps containing pH-adjustingcomponents, from the line 114. Agitation ismaiutained in the slurry tankby suitable means (not shown) and the slurry is quickly withdrawn byline116 to the filter 118. Although shown as a rotary drum filter, it may beof any desired type. The filter produces a catalyst cake which maybewashed by water from a source not shown and scraped from the filter bydoctor blade 122. Excess aqueous material is removedirorn the system byline 124. Catalyst goes by route 126 to wash tank 128. A slurry ofcatalyst in wash water may be brought by line 130 back to regeneratorS0. The chlori nator effluent removed by line 108 is conveyed to baffletower 132 where the metal chlorides may be condensed from; the vapors bycooling with air or by indirect conthe system by line 135. The gases areremoved by line 136 and conveyed to knock-out drum 140 wherehydrogenchloride is removed byline. 142 and returned tothe treating zone 12, vialines 142, 20 and 14. The following examples of the process of thisinvention are'not to be considered limiting.

' Examp lgz I F. and 50%boils below 665 F, contained 0.97% sulfur, 0.18%nitrogen, 25 ppm. nickel, measured as Ni-O and 51 ppm. V measured as V05. j This crude oil is contacted in a rocking autoclave for aboutminutes "at'a temperature of about 70 and a pressure of 50 p.s.i;g.,with about 3.3 weight percenttof anhydrous HCl. The.

an ILG tion of the silica-alumina catalyst is continuously removed fromthe cracking reactor and brought to a regenerator. Average residencetime in the regenerator is about 5 minutes at a temperature of about1100 F. before catalystis returned to the cracking reactor at a carbonlevel of about 0.4%.

About 0.2 pound of virgin catalyst is added to the cracking reactor foreach barrel of feed processed to make up for catalyst which isinadvertently lost from the sys- 'tem or which, due to physical"deterioration, is discarded from the system. About 25% of the crackingcatalyst inventory, poisoned to a metals level or about 450 ppm.

, nickel, and 3200 ppm. vanadium, is sent each day as a side stream fromthe regenerator to demetallization. In the demetallization process thecatalyst is held in air for about an hour at'about 1300 F. and then sentto a sulfiding zone where it is fluidized with H 8 gas at a temperatureof about 1175 F. for about an hour. The'catalyst is then purged withflue gas at a temperature of about 575 F. and chlorinated in achlorination zone with an equirnolar mixture of cl and CCL; at about 600F.

After about 1 hour no trace of vanadium chloride can be found in thechlorination efiluent and the catalyst is quicklywashed with water. A pHof about 2 is imparted to this wash medium by chlorine entrained in thecatalyst and the wash serves to remove nickel chloride. Thedemetallization procedure removes about 60% of the nickel and about 25of the vanadium on the catalyst. The

i treating zone." 7 j tact with-water introduced by line 134 and removedfront acid sludge produced is allowed to settle and the oil is decantedoff. The oil was obtained in a yield of abou't' 89' weight percent ofthe crude to the autocl'ave and .analyzes 7.4 ppm. nickel oxide and 21.5ppm vanadium, Thetreated oil is fractionated and the hydrogen The 400F.+bottorns fraction amounting to about 66 percentof the treated oil andcontainingaboutlll ppm.

7 nickel and 32.6 ppm; vanadium is blended with a portion ofcycle oilfrom the cracker for a metals content of about 7 ppm. nickel andcatalytiocra cking teed. a

In. thecatalytic cracker the feedstock contacts a syn- 20 p m; vanadiu min the .thetic gel silica-alumina catalyst, having an A1 0 content ofabout 25% at a temperature of about'900 to 925 F. and a pressure ofaboutS p.s.i.g. The cracked products are introduced to a fractionatorwhere approxi-' mately gasolineand other low boilingcomponents areremoved. The residue, including gas-oil fractions,

is r ycled to the cracker for further processing. por- Q 2470 ppm. V 0isnea'ch day sentas a side stream from s V chlorination efiluent isconducted to a zone where the metal chlorides are removed and the gasesare separated so that hydrogen chloride may be recycled back to the 7Example 11 p A The bottoms from an atmospheric crude oil distillationhad an API gravity of 18.7, a kinematic viscosity at 122 F. or 242.7 andat 210 F. of 27.76 and a pour'point of F. This light reduced'cr'ude hadan initialboiling point of 486. F. and contained 10% of materialsboiling below 710 F., and 50% boiling below 951 F. (converted toatmospheric pressure). 0.37% nitrogen, 1 .4% su'lfur, 0.61%' oxygen,4.898% pentaneinsolubles, 49 ppm. Ni() and p.p.rn. V 0 This stillbottoms was contacted with n-pentane in a solvent/oilratio 0113 to landabout 6'weight percent of .xylene sulfonic acid, based on the weight ofthe tower bottoms, and was mixed and agitated for about /2 hour atatmospheric pressure and a temperature of about 75 F. After treatmentthe sludgeis allowed to settle and the treated oil is decanted oifandthen the acid is removed by means of a water-wash. The treatedoil,substantially 'free of the acid, amounts to a yield of 83 weight percentbased 'on the tower bottoms to the treating zone.

oil contains 12 ppm; nickel, 32 ppm; vanadium, a carbon residue of 3.88%and a sulfur content of 0.9 weight" v percent, The treated oil isblended with a portion of cycle .oil'from the cracker for a metalscontent of about 7.5 ppm. nickel and 20 ppm. vanadium in the catalyticcracking feed. In the catalytic cracxed the feed contacts a syntheticgel silica-alurnina catalyst having an A content of about 25% at atemperature of about 95.0 to 975F. and'a pressure' of about 5 p.s.i.g.The cracked products are introduced to'a iractionator where a 55% yieldof gasoline and other components is removed, T be 'cycle gas oil isrecycled to thecracker for further processing, "A portion of thesilica-alumina catalyst is continu- 'ously removed froin the crackingreactor and brought to, c

a r'egenerator. Average residence time in the regenerator is about 5minutes at a temperature of about 1100 F. be-

fore returning to the, reactor, at a carbon level ofless than 1 about0.5%. in I a a 7 About 30% perday of the cracking catalyst inventory,poisoned to'a metals levelof about 405 ppm. NiO and 3 V the regeneratorto demetal-lization. In the demetallization process the catalyst is;held "in air for about an'hour at It contained about a The about 1300 F.and then sent to a sulfiding zone where it is fluidized with'H s gas ata temperature of about 1175 F. for about 1 hour. Dilute nitric acid isbrought in contact with the sulfided catalyst and the slurry is aeratedfor about 10 minutes at a temperature of 200 F. to convert nickelpoisons to dispersible form and remove them. The catalyst is then washedwith an ammonium hydroxide solution having a pH of about 8 to 11,removing the available vanadium. The catalyst, substantially reduced innickel and vanadium content is filtered from the wash slurry, dried atabout 350 F. and returned to the regenerator. Thetreated catalystanalyzes a metals content of 160 p.p.m. nickeland 1855 p.p.m. vanadium.

Example I III A third run was conducted with a Sour West Texas asphalthaving an initial boiling point of about 1050 F., a specific gravity of8.9 API, 21 Conradson carbon content of about 19.6% and a metals levelof 30 p.p.m. nickel oxide and 58 p.p.m. of vanadium pentoxide. Theasphalt contained 11.99% pentane insolubles and had a Furol viscosity at250 F. of 158.5. It was treated for 2 hours at a temperature of about250275 F. and a pressure of about 250-500 p.s.i.g. with about 15 weightpercent of anhydrous HCl in a rocking autoclave. The mixture wasextracted with n-pentane in a solvent-to-oil ratio of 4 and theratlinate phase containing the sludge was drawn oif from the bottom ofthe autoclave. The extract phase containing the treated oil and solventis distilled to remove the n-pentane and HCl. The extracted oil,amounting to about 77 weight percent yield based on the asphalt andanalyzing 7.6 p.p.m. nickel oxide, 21.6 p.p.m. vanadium pentoxide andhaving a Conradson carbon content of about 7%, is diluted with a portionof cycle oil from the cracker for a metals content of about 4.8 p.p.m.nickel oxide and 13.5 p.p.m. vanadium pentoxide in the catalyticcracking feed. The feed is catalytically cracked at a temperature ofabout 950 F., at 10 p.s.i.g. pressure in the presence of a syntheticsilica-alumina catalyst containing about 13% A1 0 The cracked productsare introduced to a fractionator where a 60% yield of gasoline and otherlow boiling components are removed. The gas oil fraction is recycled tothe catalytic cracker and the residue, products boiling above about 950F., is recycled to the acid treating zone for further processing. Aportion of the silica-alumina catalyst is continuously removed from thecracking reactor and brought to a regenerator. Average residence time inthe regenerator is about minutes at a temperature of about 1100 F.,before returning to the reactor at a carbon level of about 0.5%.

About 20% of the cracking catalyst inventory poisoned to a metals levelof about 380 p.p.m. nickel and 2410 p.p.m. vanadium, is each day sent asa side stream from the regenerator to demetallization. In thedemetallization process the catalyst is held in air for about an hour atabout 1300 F in H S for about an hour at about 11 5 0 F., in mixed C1and CCL; for an hour at about 600 F. and washed with water. The catalystis filtered from the wash slurry, dried at about 350 F. and returned tothe regenerator. The treated catalyst is analyzed and shows a metalscontent of 150 p.p.m. nickel and 1810 p.p.m. vanadium.

Thus, this invention provides for overcoming poisoning efiects by abalanced process which includes acid pretreatment of the cracking feedand cracking catalyst demetallization.

It is claimed:

1. A method for preparing gasoline which comprises contacting ahydrocarbon cracking feedstock boiling above the gasoline range andcontaining at least about 1 p.p.m. nickel and at least about 1 p.p.m.vanadium by including in said feedstock the residual product obtained ashereafter set forth, with a solid cracking catalyst under crackingconditions to produce gasoline, removing from the cracking systemcatalyst contaminated with metal contarninant, the removed catalystcontaim'ng at leastlabout 50 p.p.m. nickel and at least about 50 p.p.m.vanadium, demetallizingthe catalyst to remove at least 50% of the nickeland at least 15% of the vanadium from the catalyst, returning thecatalyst to said cracking system and recovering gasoline product fromsaid cracking; said feedstock containing the residual product obtainedby treating a mineral oil hydrocarbon boiling above about 650 F. andcontaining at least about 5 p.p.m. nickel and at least about 5p.p.nnvanadium with a metaland -asphalt precipitating acid to reduce byabout 10 to the content of said contaminant, said residual productcontaining at least about 1 to about 25 p.p.m. nickel and at least about2 to about 50 p.p.m. vanadium and less metal contaminant than saidmineral oil hydrocarbon. q

2. The process of claim 1 in which catalyst demetallization includescontact of the catalyst with a vapor reactive withametal contaminant.

3. The process of claim 1 wherein the acid treatment is carried out bycontacting the mineral hydrocarbon oil with an acid selected from thegroup consisting of hydrogen chloride and xylene sulfonic acid, andseparating an acid sludge containing a substantial portion of the metalcontaminant andcoke precursors originally present in said hydrocarbonoil. a

4; The process of claim 1 in which the lyst is silica-alumina.

5. The process of claim 1 in which the demetallization step includesregenerating the catalyst at about 950 to 1200" F contacting theregenerated catalyst with a molecular oxygen-containing gas at atemperature of about 1000to 1800 F., sulfiding the poisoning metalcomponent in the catalyst by contact with a sulfiding agent at atemperature of about 500 to about 1500 R, chlorinating the poisoningmetal containing component on the catalyst by contact with anessentially anhydrous chlorinating agent at a temperature of about 300to 1000 F., contacting the catalyst with a liquid essentially aqueousmedium ;to remove soluble poisoning metal chloride from the catayst.

6. The process of claim 5 in which the sulfiding is performed by contactwith H 8.

7. The process of claim 5 in which the chlorinating is performed bycontact with an equimolar mixture of C1 and CCl.;.

8. A process of treating a residual hydrocarbon oil boiling above thegasoline range and containing about 25 to about 500 p.p.m. nickel andabout 50 to about 1000 p.p.m. vanadium, comprising the steps of treatingsaid hydrocarbon in an acid treating zone with a non-oxidizing metaland-asphalt precipitating acid to reduce by about 50 to 90% the content ofsaid contaminant metal, obtaining the treated oil from an acid sludgecontaining a substantial portion of said metal contaminant, removing theacid from the treated oil, fractionating the treated oil to removecomponents boiling below about 400 F., contacting the residual fractionboiling above about 400 F. and containing at least about 1 to about 25p.p.m. nickel and at least about 2 to about 50 p.p.m. vanadium with asolid cracking catalyst under cracking conditions to produce gasoline,removing metal contaminated catalyst, the removed catalyst containingmore than about 200 p.p.m. nickel and more than about 500 p.p.m.vanadium, demetallizing the removed catalyst to remove at least 50% ofthe nickel and at least 15% of the vanadium, returning the demetallizedcatalyst to said cracking system and re covering the product from saidcracking.

9. The process of claim 8 in which the treatment with the non-oxidizingmetaland -asphalt precipitating acid is conducted in the presence of asolvent for the hydrocarbon oil.

10. The process of claim 8 in which the acid is an anhydrous hydrogenhalide.

1 1. The process of claim 10 in which the acid is HCI.

cracking cata- 12 The, process ofv claim 8 in: which the acid isahydrocarbonsulfonic acid. I t I 13;, The process of claim;12 in whichthe acid .isxylene sulfonic acid. V I v 14-. The process-of claim :8 inwhichlthesolvent is a liquidhydrojcarbon of 3- to: 7 carbon atoms.

15.? The process of claim 8 whereinthe residual hydrocarbon oili istreated with hydrogen chloride at elevated temperatures and pressuresand. then extracted with npentane to form an acid-sludge raflinate andan-oil-extract Containing substantially less metal contaminant thansaid, I hydrocarbon oil. e

16. The process of claim8 whereinthe solid cracking catalyst is asynthetie gel silica-based cracking-catalyst;

17. The process of claim 8 wherein catalyst, demetallization includescontact ofthe catalyst with; a vapor reactive with ametal contaminan-t;

, 25 to about 500p.p.m. nickel and about 5.0 to about 1 000 p.p.m.vanadium; comprising the; steps of treating said hydrocarbon'in an acidtreating zone with anon-oxidizing metaland -asphalt precipitating acid"to reduce by about 7 50 to 90% the content of said contaminantmetal,obtain- 7 fing the treated oil from an acid sludge containing a substant-ial portion of said mctalcontaminant; removing the acid from thetreated oil, fractionatingi the treated oil to remove components boilingbelow about 400 F., contacting the residual fraetion boiling above about400 F. t

, andfcontaiuing at least: about 1 to a eutzs' ppm. nickel and at leastabout 2 to about 50, ppm; vanadium with a solid cracking catalyst undercracking conditions to produce gasoline, removing metal contaminatedcatalyst from the; cracking system,v regenerating the catalyst at about950 to 1200 F., contacting the regenerated catalyst with a molecularoxygen containing gas at a temperature of aboutlOOO tol800 F., sulfidingthe poisoning metal component. on the catalyst by contact With H 8 at atemperature of about to 1500 F; chlorinating the poisoning metalcontaining component on the catalyst by contacting with an essentiallyanhydrous equimolar mixture of C1 and CCL, at a temperature of about 300to 1000 F., contacting the'catalyst with'an'esse'ntially liquid aqueousmedium to remove soluble poisoning metal chloride from the catalyst,returning the catalyst to said cracking system, the said demetallizationremoving about 50% of the nickel and at least about 15% of the vanadium,and recovering gasoline product from said cracking. 7 20. The process ofclaim 19 in which the treatment with the non-oxidizing metalanda'sph'alt precipitating acid is conducted in the presence of a solventfor thehydrocarbon oil., Y

' RetereneesCitedin the file of thisjpatent UNITED STA TES PATENTS2,758,097 Doherty ct al.- Aug. 7, 1956 7 2,778,777 Powell Jan. 22, 19572,800,427 Junk et a1,; July 23, 1957 7 2,865,838' Mills Dec. 23, 19582,902,430 Kimberlin Q Sept. 1, 1959 2,948,675 cas et-al. Aug; 9, 1960UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,165,462 January 12, 1965 Bernard 8. Friedman et a1.

It is hereby certified that error appears in the above numbered pat-,ent requiring correction and that the said Letters Patent should readas corrected be.1o*

Column 9, line 13, for "38,810" read 39,810

; line 63, for vandium" read-,- vanadium columnlO, line 37, for"chlorinatngjg' read chlorinating column 15, line 15, for "acfcaly st"read Catalyst column 16, line 58, for cracked" read cracker column 20,line 10, for "50" read 500 Signed and sealed this 16th day of November1965 (SEAL) Attcst:

ERNEST W. SWIDER EDWARD J. BRENNER Commissioner of Patents AttestingOfficer

1. A METHOD FOR PREPARING GASOLINE WHICH COMPRISES CONTACTING AHYDROCARBON CRACKING FEEDSTOCK BOILING ABOVE THE GASOLINE RANGE ANDCONTAINING AT LEAST ABOUT 1 P.P.M. NICKEL AND AT LEAST ABOUT 1 P.P.M.VANADIUM BY INCLUDING IN SAID FEEDSTOCK THE RESIDUAL PRODUCT OBTAINED ASHEREAFTER SET FORTH, WITH A SOLID CRACKING CATALYST UNER CRACKINGCONDITIONS TO PRODUCE GASOLINE, REMOVING FROM THE CRACKING SYSTEMCATALYST CONTAMINATED WITH METAL CONTAMINANT, THE REMOVED CATALYSTCONTAINING AT LEAST ABOUT 50 P.P.M. NICKEL AND AT LEAST ABOUT 50 P.P.M.VANADIUM, DEMETALLIZING THE CATALYST TO REMOVE AT LEAST 50% OF THENICKEL AND AT LEAST 15% OF THE VANADIUM FROM THE CATALYST, RETURNING THECATALYST TO SAID CRACKING SYSTEM AND RECOVERING GASOLINE PRODUCITFROMSAID CRACKING; SAID FEEDSTOCK CONTAINING THE RESIDUAL PRODUCTOBTAINED BY TREATING A MINERAL OIL HYDROCARBON BOILING ABOVE ABOUT650*F. AND CONTAINING AT LEAST ABOUT 5 P.P.M. NICKEL AND AT LEAST ABOUT5 P.P.M. VANADIUM WITH A METAL- AND -ASPHALT PRECIPITATING ACID TOREDUCE BY ABOUT 10 TO 90% THE CONTENT OF SAID CONTAMINANT, SAID RESIDUALPRODUCT CONTAINING AT LEAST ABOUT 1 TO ABOUT 25 P.P.M. NICKEL AND ATLEAST ABOUT 2 TO ABOUT 50 P.P.M. VANADIUM AND LESS METAL CONTAINMENTTHAN SAID MINERAL OIL HYDROCARBON.